| 摘要 |
<p>PURPOSE: To maintain the high quality of a 1st toner image on a photoreceptor drum, to separate and recover a 1st toner without accumulating it in a 2nd developing device in the case of the 1st toner intrudes into the 2nd developing device and to easily obtain a high-quality two-color image without exerting an influence on a 2nd toner image by the 1st toner. CONSTITUTION: A magnetic one-component non contact alternate electric field developing method using magnetic toner (2nd toner 19) is adoped for 2nd developing. The average particle diameter of the 1st toner 18 is set larger than that of the 2nd toner 19, the electrification amount of the 1st toner 18 after the toner intrudes into the 2nd developing device 6 is reduced, and the carrying force of the 1st toner 18 by the developing sleeve 7 of the 2nd developing device 6 is weaker than that of the 2nd toner 19. Since the carrying force of the 1st intruding toner 18 by the developing sleeve 7 is weak, the 1st toner 18 is suspended by developing bias in a developing area and separated and discharged to the outside of the 2nd developing device 6.</p> |
